Wireless devices can enter a lower power state, or idle mode, when not involved in an active communication session, for example, to conserve network resources as well as to conserve power storage on the wireless device. To notify a wireless device in the idle state of the arrival of data for delivery to the wireless device, the communication system can send a paging message to the wireless device. For example, a controller node, such as a mobility management entity, can store an identity of the last known access node that the wireless device was in communication with (when it entered the idle mode) and send a first paging message to the last known access node. If the wireless device does not respond to the first paging message, a second paging message can be sent to a group of access nodes, referred to as a tracking area. Tracking areas are configured by the communication network provider.
The group of access nodes comprising the tracking area are each assigned a tracking area identifier (TAI), which is broadcast by each access node over the communication network. When a mobile wireless device detects a new TAI, the wireless device sends a tracking area update (TAU) message to the communication network to indicate its new tracking area. Tracking area dimensioning must be carefully considered by the network operator. When a tracking area is too large, paging operations generate substantial network signaling overhead. When a tracking area is too small, wireless devices send TAU messages more frequently, also generating substantial network signaling overhead, as well as negatively affecting power storage and processing of the wireless device.